Soil-Borne Bacteria (Pectobacterium carotovorum)

Overview

Cabbage infected with soft rot (Pectobacterium Carotovorum

Bacterial pathogens are single-celled organisms that have a rigid cell wall but lack a membrane around the nucleus. One example is Pectobacterium carotovorum, which causes bacterial rots in multiple crops, especially potato and onion. P. carotovorum affects the bulbs or tubers by soaking and softening the inner flesh and causing it to turn a dark brown–black color. This disease is most common when soil temperatures are high (90°F and above) along with the presence of moisture.

DamageBacteria will enter through the wounds of plants then cause infection. P. carotovorum damages the bulbs or tubers by soaking and softening the inner flesh and causing it to turn a dark brown-black color.

Management

There is no cure once plants are infected, therefore early management is essential.

P. carotovorum spreads through water, so furrow, flooding, or overhead irrigation that leaves standing water may contribute to disease incidence.

White Flies (Family: Aleyroidae)

Overview

Whiteflies (Bugwood.org)

Adults are 1.5-2.5 mm long, have white wings, and typically form large colonies during warm temperatures on the underside of leaves. Economic damage in Utah mostly occurs in greenhouses and high tunnels. Whiteflies are known to develop resistance to insecticides, so treatment is not generally recommended for homeowners or small production.

DamageBoth the adults and nymphs will use their piercing-sucking mouthparts to feed on various vegetable crops, especially those in the Cubiritcaceae and Solanaceae families. Affected plants will have leaves that turn yellow, appear dry, and eventually fall off. Similar to aphids, whiteflies will excrete a sugary substance called honeydew on the leaves.

Management

Encourage natural enemies (beneficial insects) to the area such as parasitic wasps, lady beetles, and lacewings.

Remove infested foliage or spray them down with water.

Inspect transplants for any signs of whitefly populations before planting in the field.

Set up sticky traps in greenhouse or high tunnel to monitor populations.

Adults can range from 4-6 mm long. They are brown with yellow, black, and red markings. They are identified by a triangle pattern on their upper back. Lygus bugs are commonly found in Utah and the crop damage can be an economic threat.

DamageDamage has recently been reported on seed alfalfa in Idaho’s Treasure Valley, however, multiple vegetables are susceptible as well. Both adults and nymphs will use their piercing-sucking mouthparts to cause seeds to shrivel, discolor foliage, and prematurely drop buds, flowers, and fruits.

Cabbage Maggots (Delia radicum)

Overview

Cabbage Maggot (Delia radicum) (Bugwood.org)

Adult flies typically emerge in early May, though sporadic in Utah this pest can cause serious economic loss to crops. Adult flies and larvae are both about half a centimeter long. The larvae (maggots) are white and are found on beets, broccoli, Brussels sprouts, cabbage, cauliflower, celery, collards, kohlrabi, radishes, turnips, and other brassicas.

DamageThe larvae will feed and tunnel through the taproots of host crops, which can cause wilting, reduced growth, and leave plants susceptible to fungal and bacterial decay.

Management

Implement a crop rotation between suscetible crops and unrelated crops.

Consider using raised soil beds to increase soil drying and warming.

Remove all plant residue at the end of the season to prevent overwintering life stages.